JPS62136021A - Mask structure for lithography - Google Patents

Abstract

PURPOSE:To set an alignment and a gap with a material to be worked in high accuracy by providing a through hole which can pass an energy beam at a position corresponding to a scribing line of the material. CONSTITUTION:An electron beam is emitted from above to a pore 5 while moving a mask structure 13 relatively rightward or leftward to a semiconductor wafer 10 to detect secondary electrons generated from the wafer 10. In this case, the detected value of the electrons is different according to the presence or absence of an alignment mark, and the disposition of the pore 15 of the structure 13 when the detected value is maximum is in the state that the pore 15 of the structure 13 is disposed accurately to the scribing line 12 of the wafer. The relative positional relationship between the wafer 10 and the structure 13 can be set accurately by detecting a plurality of pores 5. The electron beam which has passed the pore 5 is measured in case of measuring a gap. Thus, an alignment and the gap can be set in high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to mask structures used in lithography. Such mask structures are used, for example, in the manufacture of semiconductor devices.

[Prior Art] It is widely used in industry, particularly in the electronics industry, to manufacture various products by partially altering the surface of a workpiece using lithography technology. Products with the same surface deterioration can be manufactured in large quantities. The surface of the workpiece is altered by irradiation with various types of energy rays, and in this case, a mask partially disposed with an energy ray absorbing material is used to form a pattern. As a mask like this.

When the irradiated energy beam is visible light, black paint is partially applied on a transparent substrate such as glass or quartz, or a visible light absorbing thin plate or thin film of metal such as Ni or Cr is partially applied. was used.

However, in recent years, as finer pattern formation and lithographic processing techniques are required in a shorter time, X-rays and particle beams such as ion beams have come to be used as irradiation energy beams. In the case of visible light, most of these energy rays are absorbed when they pass through the glass plate or quartz plate used as the mask forming member. Therefore, when using these energy rays, the glass plate or quartz plate must be used. Therefore, in lithography processing technology that uses X-rays or particle beams as irradiation energy beams, various inorganic thin films such as silicon nitride, boron nitride, silicon oxide, titanium, etc. Alternatively, various organic thin films such as polyimide, polyamide, or polyester thin films, or these VI layer films, may be used as energy transmitters, and gold, platinum, nickel, tungsten, palladium, rhodium, indium, etc. may be applied on these surfaces. A mask is formed by partially applying metal as an energy ray absorber. Since this mask does not have self-retaining properties, it is supported by a suitable holder.

Conventionally, a mask structure constructed in this manner has been used, as shown in a cross-sectional view in FIG. This is done by attaching an adhesive to one end surface (in the figure, the upper end surface) of the annular holding substrate 3 at the periphery of the energy ray transparent holding thin film 2, which has an energy ray absorbing mask material l applied on one side in a desired pattern. It was formed by pasting using 4. Incidentally, FIG. 8 is a plan view of the holding substrate 3.

By the way, when performing photolithography processing using the above mask structure, the mask pattern of the mask structure must be accurately set on the workpiece, such as a silicon wafer (the surface of which is coated with photoresist). It is necessary to accurately set the alignment and the distance (gap) between the surface of the workpiece and the mask material holding thin film of the mask structure.

Therefore, in lithography processing using a conventional mask structure, holding the surface of the workpiece and the mask structure 6. Marks for alignment are attached to the HIQ, and after placing them almost parallel, a visible light beam is irradiated from the holding thin film side to detect the degree of agreement between both marks, and then alignment is performed. The gap was set while detecting the reflected light on the surface and the reflected light on the surface of the workpiece.

However, since this type of detection involves detecting visible light that has passed through the holding thin film, the detection accuracy decreases due to scattering and/or absorption in the holding Q [film, etc. It is not possible to obtain sufficient alignment and gap setting accuracy in photolithography.

Furthermore, in order to improve the detection accuracy of alignment marks, it is possible to use electron beams, ion beams, X-rays, ultraviolet rays, and vacuum ultraviolet rays instead of visible light, but these are subject to significant scattering and absorption by the holding thin film. Therefore, it is practically unusable.

[Object of the Invention] In view of one or more of the conventional techniques, an object of the present invention is to provide a lithography mask structure that can perform alignment with a workpiece and gap setting with high precision.

[Summary of the Invention] According to the present invention, the above object is to provide a mask material holding thin film with a plurality of through holes through which energy beams can pass through for detecting the alignment state with the workpiece. This is achieved by a lithography mask structure characterized in that the through hole is provided at a position corresponding to a scribe line of a workpiece.

[Example] Fig. 1 shows a plan view of a specific example of a lithography mask structure according to the present invention, and Fig. 2 shows the sections ■-■ in Fig. 1.
(However, FIG. 1 and FIG. 2 do not completely match) This specific example is a mask structure for X-ray photolithography.

The mask material 1 is applied to one side of the holding thin film 2 in a desired pattern. As the mask material 1, for example, a thin film of about 0.5 to 0.7 μLm of gold, platinum, nickel, tungsten, tantalum, copper, molybdenum, palladium, rhodium, etc. can be used.

The holding thin film 2 is in a stretched state and its peripheral portion is bonded to the deep holding substrate 3 with an adhesive 4.

As the holding thin film 2, organic thin films such as polyester, polyamide, polyimide, parylene, etc., and inorganic thin films such as silicon nitride, boron nitride, and silicon nitride can be used. The thickness of these thin films 2 is, for example, 2 to 20 J.
It is about Lm.

The holding thin w12 is bonded to the holding substrate 3 in a state where it is isotropically stretched at a stretching rate of, for example, about 5 to 20% (area ratio).

As the holding substrate 3, silicon, glass, quartz, phosphor bronze, brass, iron, nickel, stainless steel, etc. are used, for example.

As the adhesive 4, for example, epoxy type, rubber type, or other suitable adhesives are used, such as solvent type, thermosetting type, or photocuring type.

The holding thin H2 is provided with a plurality of small holes 5 (four in the figure) that can penetrate from the front surface to the back surface at positions where the mask material 1 is not applied.

The shape of the small hole 5 is not particularly limited, and may be any of rectangles such as squares and rectangles, squares such as triangles, hexagons, and hexagons, round shapes such as circles and ovals, and combinations thereof. However, it is particularly preferable to make the small hole 5 circular.
The size is not particularly limited, and may be set as appropriate depending on the alignment with the target workpiece, the state of the gap, the type of energy beam used for detection, and the required detection accuracy. be able to. Examples of energy rays used for detection include electron beams, ion beams, X-rays, ultraviolet rays, and vacuum ultraviolet rays, and furthermore, visible rays and infrared rays can also be used. - For example, in the case of detection using an electron beam, the diameter of the small hole 5 is about lθ~30
In addition, two or four small holes 5 are provided axially symmetrically with respect to the symmetry axis of the annular holding substrate 3. However, the position where the small hole 5 is provided is appropriately set according to the pattern of the mask material 1 in the mask structure.

In photolithography processing, for example, in the manufacturing process of semiconductor elements, as shown in FIG.

A large number of semiconductor elements 11 having the same pattern are formed on a semiconductor wafer 10 which is a workpiece. After pattern formation, these semiconductor elements 11 are cut along boundary lines (scribe lines) 12 to form individual semiconductor element chips.

In such photolithography processing, a pattern formed by arranging a plurality of unit patterns of the above-mentioned semiconductor elements in parallel is used as a pattern of the mask material 1 of the mask structure. In FIG. 1, four unit patterns 7 of semiconductor elements are arranged. These unit patterns 7 are divided by lines 8 corresponding to the scribe lines 12 of the semiconductor wafer 10, and in photolithography, they are divided by lines 8 corresponding to the scribe lines 12 of the semiconductor wafer 10 and the mask structure 13 determined in advance. 8 and perform alignment with accurate correspondence (see Figure 4).
, and then irradiation with energy rays such as X-rays is performed.

Then, the relative position between the semiconductor wafer IO and the mask structure 13 is further changed, and the unirradiated semiconductor elements are aligned and irradiated with energy beams in the same manner as described above, and this process is repeated.

For example, there is a scribe line 12 on the semiconductor wafer lO.
An alignment mark formed, for example, as a recess is provided at an appropriate position by etching or the like. In this way, when an alignment mark is formed on the scribe line 12 of the semiconductor wafer 10, the small hole 5 in the mask structure corresponds to the alignment mark, as shown in FIG. It is formed on the line 8 corresponding to the scribe line. The scribe line 12 of the conductor wafer 10 has a width of, for example, about 30 g. preferable.

The method of forming the small holes 5 in the holding thin film 2 is selected depending on the material of the holding thin film 2, but for example, a laser beam (
Excimer laser, argon laser, etc.) method, dry etching (R, I.

Examples include a method using chemical etching (hydrazine etchant, etc.), a method using mechanical means (milling, etc.), and a method using mechanical means (milling, etc.). Two or more of these methods may be used in combination.

It is preferable to form the small holes 5 in a step near the final step of creating the mask structure, thereby preventing a decrease in the small hole position accuracy due to post-processing.

Note that a good degree of accuracy can be achieved by forming a pattern for forming small holes simultaneously with the step of forming the mask material 1 on the holding thin film 2.

As shown in FIG. 5, one or more mask structures 13, such as the one shown in FIG. 5, are used in close proximity to the semiconductor wafer 10. A resist layer 14 is formed on the surface of the semiconductor wafer 10. While moving the mask structure 13 in the left-right direction relative to the semiconductor wafer 10, the small hole 5 is irradiated with an electron beam from above, and secondary electrons generated from the semiconductor wafer IO are detected. At this time, the alignment mark (
For example, the detection value of secondary electrons differs depending on the presence or absence of a recess (as shown in the figure), and when this detection value takes an extreme value, the small hole 5 of the mask structure 13 is accurately positioned relative to the scribe line 12 of the semiconductor wafer. It is placed in the . By similarly detecting a plurality of small holes 5, the relative positional relationship between the semiconductor wafer 10 and the mask structure 13 can be made accurate. Similarly, when measuring the gap, the electron beam passing through the small hole 5 is measured.

Of course, a method of detecting out-of-focus using an optical lens can also be used.

□In addition to the above-mentioned electron beam, energy beams used for alignment or gap detection when using the mask structure of the present invention include ion beams,
X-rays, ultraviolet rays, vacuum ultraviolet rays, and even visible light and infrared rays can be used, and the alignment mark on the workpiece side must be formed so that it behaves differently from the surrounding area in response to these energy rays. Bye.

In the mask structure of the present invention, it is also possible to use a laminated film in which two or more 9i films are laminated as the mask material holding thin film.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1: A mask structure as shown in a vertical cross-sectional view in FIG. 6 was prepared.

In FIG. 6, similar members to those in FIG. An adhesive 4 is applied to the upper outer slope 3b, thereby bonding the holding thin film 2 and the holding substrate 3. The angle 0 of the slope is suitably about 5 to 15 degrees, and in this example, it is set to io degrees.

According to the mask structure of this embodiment, the holding thinness II!
The mask material holding plane 22 is not affected by the adhesive 4 and can achieve good flatness that is the same as the flatness of the upper flat end surface of the holding substrate 3, thereby improving the accuracy of lithography processing.

First, about 10% of the annular holding substrate 3 is attached using adhesive 4.
Polyimide film (7,5JL) was stretched isotropically at a stretching rate of
m thickness, product name: Kapton membrane) was adhered.

Next, photoresist AZ-1350 (manufactured by Sibley) was applied on the holding thin film to a thickness of 0.5 gm under specified conditions, and a diameter of approximately 15#L was applied using a quartz mask using a far-UV printing machine.
A resist pattern of two small holes of m was formed.

Next, the polyimide film at the position of the small hole pattern was removed by etching to form small holes.

Based on the two small holes thus formed.

In a predetermined process, an X-ray absorption pattern consisting of a gold film with a thickness of 0.5 gm was formed on the holding thin film by electrohoming.

Example 2: In Example 1, without etching the polyimide film, an XM absorption pattern consisting of a 0.5 lumen thick gold film was formed on the holding thin film by electrohoming in a predetermined process.

Thereafter, using the pattern as a reference, concentrated excimer laser irradiation was performed to form two small holes with a diameter of about 15 pm in the corresponding scribe line.

Example 3: Small holes were formed in the same manner as in Example 2, using an argon laser instead of the excimer laser.

Example 4: Examples 2 and 3 were performed using polyester FIJ (8 μm thick, manufactured by Toshi Co., Ltd. under the trade name Lumirror) instead of the polyimide film.
A small hole was formed in the same manner as in .

Example 5: Using a polyimide film as a holding thin film, when forming a mask pattern made of a gold film, at the same time a small hole pattern with a diameter of about lOILm was provided in the gold film on a line corresponding to the scribe line, and a small hole pattern with a diameter of about 1OILm was formed in this small hole pattern portion. Two small holes were formed in the polyimide film within a few seconds by dropping the hydrazine etchant.

[Effects of the Invention] According to the present invention as described above, in lithography processing, when aligning and setting the gap between the mask structure and the workpiece, energy ray irradiation is performed through the through hole provided in the mask material holding thin film. As a result, reflection from the workpiece can be detected using yEX with less scattering and absorption, making it possible to perform alignment and gap setting with high accuracy, thereby enabling high-precision lithography processing. be able to. Furthermore, according to 931JJ, since the through hole is provided at a position corresponding to the scribe line of the wave force I+ material, there is an advantage that alignment marks can be easily created and alignment can be performed easily.

[Brief explanation of drawings]

FIG. 1 is a plan view of the mask structure of the present invention, and FIG. 2 is a cross-sectional view taken along the line -■. FIG. 3 is a partial plan view of the workpiece, and FIG. 4 is a partial cross-sectional view showing the relationship between the workpiece and the mask structure. FIG. 5 is a partial sectional view showing how the mask structure of the present invention is used. FIG. 6 is a sectional view of the mask structure of the present invention. FIG. 7 is a sectional view of a conventional mask structure, and FIG. 8 is a plan view of its holding substrate. 1: Mask material 2: Holding thin film 3: Holding substrate 4: Adhesive 5: Small hole 8 varnish scribe line corresponding line lO: Workpiece material 12 varnish scribe line 13: Mask structure 14 Resist layer agent Patent attorney Yamashita
穣平Nj Figure 2 Figure 5 Figure 3 Figure 4 Figure 6 Melon 7F! A Figure 8

Claims (1)

[Claims] (1) In a lithography mask structure in which the periphery of a mask material holding thin film on which a mask material is to be applied in a desired pattern is held by a holding substrate, the mask material holding thin film is aligned with the workpiece. A mask structure for lithography, characterized in that a plurality of through holes are provided through which energy beams for detection can pass, and the through holes are provided at positions corresponding to scribe lines of a workpiece. .